Method of and device for controlling and/or regulating the idling speed of an internal combustion engine

ABSTRACT

A method and a device for controlling and/or regulating the idling speed of an internal combustion engine is suggested, wherein changes of the operating condition of the internal combustion engine are considered by means of a precontrol being dependent from operational characteristics dimensions of the internal combustion engine, as well as being stabilized during long term changes of the operational condition of the internal combustion engine with the assistance of a correction of the precontrol. Thereby, it is differentiated between a direct correction as well as an indirect correction, for example, additive correction of the precontrol. Block diagrams are provided for both correction possibilities. Also, a plurality of criteria are stated with the assistance of which the time range of the correction may be defined. For realizing the method with the assistance of a corresponding programmed electronic computer the precontrol and the correction for the precontrol are designed in form of support locations with intermediately disposed interpolations in one exemplified embodiment.

This application is a continuation of application Ser. No. 862,503,filed Apr. 9, 1986, now abandoned.

BACKGROUND OF THE INVENTION

The invention relates to a method and a device for controlling and/orregulating the idling speed of an internal combustion engine.

It has been known to take into consideration the operating state of aninternal combustion engine for regulating the idling speed. Theregulation of the idems speed has been performed, for example, bydetermines idling speed values for defined operating conditions of theinternal combustion engine and regulating the speed of the internalcombustion engine based on these predetermined values. Generally, withthe assistance of the known precontrols it has been possible to quicklystabilize changes in the operating state of the internal combustionengine, for example, the load change of the internal combustion engineduring switching on an air conditioning unit, for example, during theregulating of the idling speed of the internal combustion engine.

With each internal combustion engine not only short term changes in theoperational state occur, like, for example, the mentioned load jumpduring the switching on of the air conditioning unit, but theoperational state of the internal combustion engine also causes longterm changes. Such long term changes are mostly caused by aging effectsof the total internal combustion engine. These long term changes havenot taken into consideration in the known idling speed regulating,consequently, the idling speed could not been regulated to optimalvalues for a long term by the known idling speed regulator, so that thetransmissions to the idling speed were performed with higher or loweroscillations of the speed of the internal combustion engine.

SUMMARY OF THE INVENTION

In is an object of this invention to provide an improved method anddevice for controlling the idling speed of an internal combustionengine.

In contrast to the above described conventional methods the method forcontrolling and/or regulating the idling speed of an internal combustionengine according to the invention is advantageous in that long termchanges of the operational state of the internal combustion engine canbe considered during the regulation of the idling speed of the internalcombustion engine due to the correction of the precontrol of the idlingspeed regulation which is dependent from the operational state of theinternal combustion engine.

In accordance with the invention two possibilities of the correction ofthe precontrol of the idling speed regulation of the internal combustionengine are provided, namely the direct correction, that is, the changeof the precontrol values themselves or the indirect correction, that is,the change of the precontrol values by the addition of correctingvalues.

Generally, the method in accordance with the invention provides anoptimal building up of the speed of the internal combustion engine intothe idling speed, for example, from the operational conditions with thepartial load or the switching off signal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an indirect correction of the precontrol of theidling speed of an internal combustion engine;

FIG. 2 is a schematic diagram of the realisation of the indirectcorrection of FIG. 1;

FIG. 3 is a graph showing a direct correction of the precontrol of theidling speed regulation of an internal combustion engine;

FIG. 4 is a schematic diagram of the realisation of the directcorrection of FIG. 3;

FIG. 5 is a schematic diagram illustrating the correction device of FIG.4 and

FIG. 6 is a schematic diagram of a further embodiment of the precontrolof the idling speed of an internal combustion engine.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The described exemplified embodiments relate to the control and/or theregulation of the idling speed of an internal combustion engine. Thisidling speed regulation can be generally used in conjunction withinternal combustion engines, that is, in conjunction with Otto-internalcombustion engines, with Diesel-internal combustion engines, etc. Also,the exemplified embodiments described herein below are not limited toany specific circuit arrangements, but they can be realized in anyembodiment being obvious to a person skilled in the art, for example, inthe analog or digital shifting control technique with the assistance ofa correspondingly programmed microcomputer, etc.

FIG. 1 illustrates an indirect correction of the precontrol of theidling speed regulation of an internal combustion engine. The motortemperature T_(M) is illustrated on the horizontal axis of the diagram,whereby the limit temperature T_(G) is particularly shown on this axis.This limit temperature T_(G) is the motor operating temperature of theinternal combustion engine during normal operation. The characteristicscurves illustrated in the diagram are a performance graph-precontrolsignal KV, on the one hand, and an adapted precontrol signal AV, on theother hand. The constant distance between the performance graphprecontrol signal KV and the adapted precontrol signal AV is illustratedin the diagram of FIG. 1 by the constant value WK. The deviation of theadapted precontrol signal AV from the performance graph precontrolsignal KV from the constant value WK is illustrated in the diagram ofFIG. 1 by the value WT (T_(G) -T_(m)) wherein WT designates atemperature dependent value, while T_(G), as already stated, the limittemperature, and T_(M) represents the motor temperature.

The performance graph precontrol signal KV illustrated in the diagram ofFIG. 1 is a signal which is stored in any given form in a storage andwhose size depends from the operational state of the internal combustionengine. For example, if the operational state of the engine is changedby switching on the air conditioning unit, the performance graphprecontrol signal changes simultaneously with this change. The desiredidling speed of the internal combustion engine is more rapidly reachedwith the assistance of the performance graph precontrol signal KV. Theheretofore described operations are known. The long term changes of theoperational state of the internal combustion engine can be considered bythe precontrol if the adapted precontrol signal AV is used according tothe subject invention for the idling speed regulation in place of theperformance graph precontrol signal KV. This adapted precontrol signalAV results from the graph performance precontrol signal in accordancewith the diagram of FIG. 1 due to the following two equations:

    AV=KV+WK+WT (T.sub.G -T.sub.M) for T.sub.M ≦T.sub.G

and

    AV=KV+WK for T.sub.M >T.sub.G.

Accordingly, the performance graph precontrol signal KV is displacedabove the limit temperature T_(G) by the constant value WK toward theadapted precontrol signal AV, while the performance graph precontrolsignal KV is displaced below the limit temperature T_(G) not only by theconstant value WK, but also simultaneously its gradient is changed independency from the temperature dependent value WT. The constant valueWK and the temperature dependent value WK may be positive or negativevalues.

The change of the performance graph precontrol signal KV towards theadapted precontrol signal AV, illustrated in the diagram of FIG. 1, isonly one possibility of such a change. In accordance with the inventionit is also possible to change the performance graph precontrol signal KVtoward the adapted precontrol signal AV in any given manner, forexample, by a parallel displacement of KV toward AV over the total rangeof the motor temperature T_(M). With such an exemplified simplificationof the diagram of FIG. 1, there are corresponding resultingsimplifications of the realisation of the diagram of FIG. 1 (FIG. 2).

FIG. 2 illustrates a realisation of the indirect correction of FIG. 1.An idling speed regulator is designated with reference numeral 10 andhas an integral component. The reference numeral 11 indicates a lowpass. The switch S1 is designated with the reference numeral 12 and theswitch S2 with the reference numeral 15. One integrator is designatedwith the reference numeral 13 and the other integrator-with thereference numeral 16. The reference numeral 17 denotes switch S3.Connecting locations are designated with the reference numerals 14,18,21 and 22. A multiplicator is designated with the reference numeral 19.Finally, a precontrol performance graph is designated with the numeralreference 20. The idling speed regulator 10 forms a control outputsignal RA in dependency from its input signal which is a speeddifferential signal ND. The output signal RA is then fed to the low pass11, on the one hand, and to the connecting location 22, on the otherhand. The low pass 11 forms an output signal dependent from signal RA,which is fed to the two switches 12 and 15. Each integrator 13, 16 isswitched subsequent to each of the two switches, that is, the integrator13 to switch 12 and the integrator 16 to switch 15. On the one hand,switch 17 is connected with the output of the integrator 16 and, on theother hand, with an input of the multiplicator 19. The other input ofthe multiplicator 19 is admitted by the output signal of the connectinglocation 18, whose input signals consist of the limit temperature T_(G)and the motor temperature T_(M). The multiplicator forms an outputsignal in dependency from its two input signals which is designated inFIG. 2 with the formulae WT (T_(G) -T_(M)). This output signal of themultiplicator 19, as well as the output signal of the integrator 13,which is designated with WK are fed to the connecting location 14. Theoutput signal of the connecting location 14, as well as the outputsignal of the precontrol performance graph 20, which is designated withKV, are connected to connecting location 21. In dependency from itsinput signals the connecting location 21 forms an output signal AV fedto the connecting location 22. This connecting location 22 finally formsfrom their input signals the output signal LS which is an idling speedset signal.

With the assistance of the block diagram of FIG. 2 it is possible torealise the displacement of the performance graph precontrol signal KVtoward the adapted precontrol signal AV illustrated in FIG. 1. Thevalues WK and WT which determine this displacement are dependent fromthe control output signal RA, as well as from the switch positions ofthe two switches 12 and 15. The two values WK and WT are intermediatelystored by means of the two integrators 13 and 16.

The switch S1 closes when the internal combustion engine is in itsdisconnected state and when the motor temperature T_(M) is greater thanthe limit temperature T_(G). The disconnected state of the internalcombustion engine can be determined, for example, in that the total ofthe speed differential signals ND is smaller than a defined,predetermined speed differential threshold and that also the controloutput signal RA is smaller than a defined, predetermined control outputthreshold. When the switch S1 is closed, also when T_(M) >T_(G) is inthe decoupled state, it means that the performance graph precontrolsignal KV of the precontrol performance graph 20 is only corrected bysignal WK acting through switch S1. Generally in this state AV=KV+WK, asstated in the description with respect to FIG. 1.

Switch S2 closes exactly when the internal combustion engine is in itsuncoupled state and when the motor temperature T_(M) is smaller than thelimit temperature T_(G). This means that the temperature dependent valueWT changes only when switch S2 is closed. The output signal of themultiplicator 19 cannot supply an output signal because of the closingof switch S2. Only when switch S3 is closed, the multiplicator generatesan output signal which is uneven zero. Switch S3 is closed exactly whenthe motor temperature T_(M) is smaller than the limit temperature T_(G)independently from the other condition of the internal combustionengine. Generally this means that a signal is available at the output ofthe multiplicator 19 when the switch S3 is closed, having the value WT(T_(G) -T_(M)). When switch S2 is opened, this value changes only independency from the limit temperature T_(G) and the motor temperatureT_(M). If switch S2 is closed, the output signal of the multiplicator 19changes also in dependency from the temperature dependent value WT. Whenswitch S3 is closed the following equation prevails for the adaptedprecontrol signal: AV=KV+WK+WT (T_(G) -T_(M)), as has been described inconjunction with the description of FIG. 1. Not only the temperaturesT_(G) and T_(M) can change on account of the integrators 13 and 16 inthis equation in dependency from the switch positions of switches S1 andS2, but also the values WK and WT.

If only the performance graph precontrol signal KV had been connectedwith the regulation output signal RA for the idling speed set signal LSin the hitherto known state of the art, now a correction of theperformance graph precontrol signal KV toward the adapted precontrolsignal AV is possible in accordance with FIG. 2. As had been alreadyillustrated in conjunction with the description of FIG. 1 it is possibleto simplify the characteristic curve of the performance graph precontrolsignal KV and accordingly the block diagram of FIG. 2. Also, inaccordance with the invention it is possible to realise the correctionof the performance graph precontrol signal KV not only indirectly withthe assistance of an additive connection, but also directly by changingthe performance graph precontrol signals directly in the precontrolperformance graph 20. Such a realisation is described in the followingin conjunction with the exemplified embodiments of FIGS. 3, 4 and 5.

Independently from whether an indirect correction of the precontrol, asillustrated in FIGS. 1 and 2, is performed or a direct correction of theprecontrol as will be explianed in the following description, isexecuted the total operation of the correction of the precontrol isbased on that an output signal different from zero feeds the subsequentintegrators during correspondingly closed switches, thus changing theiroutput values accordingly. This change of the integrator output valuesresults in a change of the precontrol signal, which in turn results in achange of the idling speed set signal. This total operation is performeduntil the regulator output signal is zero. Generally, an error, whichhad been generated on account of the fixed predetermined values of theprecontrol and which cannot be stabilized by the idling speed regulatorwith a limited regulating stroke, is completely corrected by thecorrection of the precontrol. Furthermore, the transmission ratio duringthe transmission into the idling speed is improved.

FIG. 3 now illustrates the direct correction of the precontrol of theidling speed of an internal combustion engine. In the diagram of FIG. 3,the motor temperature T_(M) is illustrated on the horizontal axis,wherein defined temperature threshold values TS1,TS2,TS3 and TS4 areparticularly designated. Output signals are illustrated on the verticalaxis of the diagram of FIG. 3, whereby the values W1,W2,W3 as well as W4are particularly designated. The diagram of FIG. 3 generally illustratesthe characteristic curve of the performance graph-precontrol signal KVas a function of the motor temperature T_(M). This characteristic curveKV of FIG. 3 is comparable with the characteristic curve KV of FIG. 1Generally, the chracteristics curve KV of FIG. 3 is formed by foursupport locations which are connected with each other by straight lines.Thereby, it is possible to substantially improve the characteristicscurve KV of FIG. 3 in comparison with the graph of FIG. 1. It isnaturally also possible to introduce even more support locations andthereby illustrate an almost nonlinear characteristics curve KV.

The direct correction of the precontrol of the idling speed regulationdescribed in FIGS. 3,4 and 5 relates to a device with a correspondinglyprogrammed electronic computer. For this reason the values W1 . . . W4of the support locations TS1 . . . TS4 are sufficient for the computerin FIG. 3. All output values which are positioned between theaforementioned values are calculated by the computer by an interpolationwhich is adapted to the given case of application. For the correction ofthe performance graph precontrol signal KV of FIG. 3 it is not necessaryto change the total characteristic curve, as is the case in the indirectcorrection in accordance with FIG. 1, but it suffices in this case tocorrect only the four support locations. Due to the interpolation thecorrection of the supporting locations acts on the total performancegraph precontrol signal characteristics curve KV.

FIG. 4 illustrates a realisation of the direct correction of FIG. 3. Thereference numeral 24 designates an idling speed regulator with anI-component. A switch is designated with the reference numeral 25. Thereference numeral 26 designates a correcting device, while a precontrolperformance graph is designated with the numeral reference 27. Aconnecting location is designated with the reference numeral 28. Thespeed differential signal ND is fed as an input signal to the idlingspeed regulator 24. Independently from its input signal the idling speedregulator 24 forms the output signal RA which is connected to the switch25 and to the connecting location 28. The correction device 26 is alsoconnected with switch 25. The output signals are fed from the correctiondevice 26 to the precontrol performance graph 27. Finally, the outputsignal of the precontrol performance graph 27, which is characterizedwith signal KV, is connected to the connecting location 28 whichindependently from its input signals, forms the output signal LS whichis an idling speed set signal.

As already stated, the correction device 26 generates signals whenswitch 25 is closed and when the control output signal RA is differentfrom zero, with the assistance of which the precontrol of the idlingspeed regulation is corrected. As had been already stated the correctionis performed directly in the circuit illustrated in the block diagram ofFIG. 4, that is, by a direct changing of the values of the precontrolperformance graph 27. Since in the described exemplified embodiment onlythe four values W1 . . . W4 of the four supporting locations TS1 . . .TS4 in the precontrol performance graph 27 are stored, a correction ofthese values is possible in a particularly advantageous manner.Generally, the four values of the precontrol performance graph 27 arechanged with the assistance of the correcting device until theregulating signal RA becomes zero during the closed switch 25.

Since with the realisation of the correction of the precontrol with theassistance of the block diagram of FIG. 4, due to the distribution ofthe operational range of the motor temperature T_(M) with the assistanceof the supporting locations TS1 . . . TS4, a consideration of limittemperatures is no longer required, as is the case in the realisation ofthe correction of the precontrol in accordance with FIG. 2, switch 25 isexactly closed when the internal combustion engine is in its decoupledstate.

It is now possible to recognize the decoupled operational condition withthe assistance of the speed differential signal ND and the controlsignal RA, as had been already illustrated in conjunction with thedescription of FIG. 2. However, the first recognition possibilityrequires a first adaptation, that is, immediately after the internalcombustion engine had been manufactured the two threshold values for thespeed differential and the regulating output signal must be so set onthe engine test stand that a safe recognition of the decoupled conditionbe made possible.

It is therefore particularly advantageous to determine the decoupledoperational condition of the internal combustion engine by means of thefollowing method. By means of tests and experiments it had been shownthat the speed drop, for example, from the partial load range to theidling speed range engine coupled condition takes place substantiallyslower than in the decoupled operational condition. This means that at acorresponding determination of the theoretical value speed drop, theactual speed drop in the decoupled operational condition of the internalcombustion engine deviates only slightly from the stated theoreticalvalue speed drop. However, in the coupled operational condition thisdeviation is substantially larger. This difference can be used for therecognition of the decoupled operational condition of the internalcombustion engine in such a manner that after a defined, predeterminedtime period after the entering of the actual value into the controlrange of the idling speed regulating, the difference between the desiredtheoretical speed and the real actual speed is tested. If thisdifference exceeds a defined, predeterminable threshold, it means thatthe internal combustion engine is in a coupled condition. However, ifthe difference is smaller than the predetermined threshold, it meansthat the internal combustion engine is in its decoupled operationalcondition. The particular advantage of this realisation of the decoupledoperational condition is that the difference of the speed drop in thecoupled and decoupled internal combustion engine is so large in alltypes of the internal combustion engines made that the predeterminablethreshold value must not be set for each individual internal combustionengine on the engine test stand, but can be determined only once. Afirst adaptation is not required with this realisation with theassistance of the speed drop, as is the case with the realisationdescribed in conjunction with the block diagram of FIG. 2. Naturally itis possible to use the latter described realisation also with therealisation with the device of FIG. 2.

A further specific possibility of recognizing the decoupled operationalcondition of the internal combustion engine in conjunction withautomatic drives consists in that this decoupled condition is exactlypresent when on the selective lever of the automatic drive the position"DRIVE" or other driving stages are not selected.

Generally, with this direct correction of the precontrol of the idlingspeed of an internal combustion engine in accordance with FIG. 4, theidling speed set signal LS is always generated by connecting theregulator output signal RA with the performance graph precontrol signalKV, whereby in the decoupled operational condition of the internalcombustion engine the values of the performance graph precontrol signalKV are corrected in dependency from the regulator output signal RA.

A simplification of the mode of operation of the block diagram of FIG. 4resides in that when using the device in conjunction with motorvehicles, switch 25 is not closed in the decoupled condition of theinternal combustion engine, but when the speed of the motor vehicle issmaller than a defined, predeterminable limit speed. This isadvantageous in that all possible problems in conjunction with firstadaptations of the device do not occur any longer. It is thenparticularly advantageous if the switch 25 of the block diagram of FIG.4 can also be closed by external manipulation, for example, fordiagnostic purposes. Thereby it is possible to take care of errors withless expense.

FIG. 5 illustrates a realisation of the correction device of FIG. 4.Reference numeral 30 designates an idling speed regulator with anI-component. The reference numerals 31 to 35 designated switches. Eachmultiplicator is designated with the reference numerals 36 to 41. Thereference numerals 42 to 45 designate one each connecting location.Finally, one each integrator is designated with the reference numerals46 to 49. The idling speed regulator 30 is admitted at its input withthe speed differential signal ND. The idling speed regulator 30generates an output signal in dependency of ND, namely the regulatingoutput signal RA. This signal is fed to each of the switches 31 to 35.The free connecting point of switch 31 or 35 is connected to theconnecting location 42 or 45, respectively. In contrast, the freeconnecting points of the switch 32 are connected with the multiplicators36 and 37, switch 33 with the multiplicators 38 and 39, as well as theswitch 34 with the multiplicators 40 and 41, respectively. Each of themultiplicators 36 to 41 is additionally admitted with a temperaturedependent signal. These signals which are designated with the lettersT11,T22,T21,T32,T31 and T42 will be described in detail later. Each ofthe multiplicators 36 to 41 generates an output signal, whereby theoutput signal of the multiplicator 36 is connected to the connectinglocation 42, the output signal of the multiplicator 41 to the connectinglocation 45, the output signals of the multiplicators 37 and 38 to theconnecting location 43, as well as the output signals of themultiplicators 39 and 40 to the connecting location 44. Finally, eachconnecting location is connected with its output signal to one of theintegrators, that is, the connecting location 42 to the integrator 46,the integration location 43 to the integrator 47, the connectinglocation 44 to the integrator 48, as well as the connecting location 45to the integrator 49. The integrators 46 to 49 generate correspondingoutput signals in dependency from their given input signals beingdesignated with the letters DW4, DW3,DW2 as well DW1.

The correction device in accordance with FIG. 5 operates in accordancewith the following operating principle. In accordance with FIG. 3 thecharacteristics curve of the performance graph precontrol signals KV isdivided into five ranges due to the four support locations TS1 . . .TS4. This division is performed in the realisation of the correctingdevice in accordance with FIG. 5 by means of the five switches 31 to 35.Of the five switches 31 to 35 only one always closes exactly and alwaysthe one which is associated with the temperature range in which themotor temperature T_(M) is present. If the temperature of the motorT_(M) is in a temperature range which is between the two outermostsupporting locations, the regulator output signal RA is fed to twomultiplicators through the given closed switch. Each of these twomultiplicators is additinally admitted by a second input signal andforms an output signal in dependency from its two input signals withwhich it influences an integrator. The output signal of the integratoris then directly connected to the precontrol performance graph, forexample, in FIG. 1 to the precontrol performance graph 20 or in FIG. 3to the precontrol performance graph 27. The values of the performancegraph precontrol signal are changed with the output values of theintegrators.

By way of example, should the motor temperature T_(M) be greater thanthe threshold value temperature TS2, however smaller than the thresholdvalue temperature TS3. Consequently, only switch 3 would be closed inthe block diagram of FIG. 5. The regulator output signal RA is then fedover switch 33 to the two multiplicators 38 and 39. As a further inputsignal the value T32 is fed to the multiplicator 38, and themultiplicator 39 is admitted with the value T21. The two multiplicators38 or 39 generate one output signal in dependency from their two inputsignals being connected with the connecting locations 43 or 44. Thesecond input signal of the two connecting points 43 and 44 is a zero,since the two switches 32 and 34 are opened. Thereby, the two outputsignals of the two multiplicators 38 or 39 are directly fed to the twointegrators 47 or 48, respectively. The output signal of the twointegrators 47 or 48 finally forms the correcting value DW3 or DW2. Thetwo correcting values DW3 and DW 2 are now directly connected with theprecontrol performance graph 27 of FIG. 3 and influence additively thevalues W3 and W2, for example. Generally, the characteristics curve ofthe performance graph precontrol signal KV of FIG. 3 is displaced withthe assistance of the two correcting values.

If the motor temperature is outside of a temperature range which islimited by the two outermost temperature threshold values TS1 and TS4,the regulator output value is fed directly to the integrator over thegiven closed switch, without being multiplied with any other values. Inthis case the precontrol performance graph 27 of FIG. 4 is directlyinfluenced by the integrator.

When looking at the characteristics curve of the performance graphprecontrol signals KV of FIG. 3, only the two values of the outputvalues W1 . . . W4 are corrected at a given motor temperature T_(M)which limit the range in which the motor temperature is present. If themotor temperature is below the smallest temperature threshold or abovethe greatest temperature threshold, only the output value of thistemperature threshold is corrected.

If one of switches 32 to 34 is closed, the regulator output signal RA,as already stated, is fed to one of the multiplicators 36 to 41. Each ofthese multiplicators, as already stated before, is admitted with afurther input signal. For this input signal the generally followingrelationships are valid. If the motor temperature T_(M) is larger than afirst general temperature threshold TSX, however smaller than a secondgeneral temperature threshold TSY, the relationshipTX1=(TSY-T_(m)):(TSY-TSX) is valid for the second input signal of themultiplicator, whose output signal indirectly influences the correctingvalue DWX. For the second input signal of the second multiplicator,whose output signal influences the correcting value DWY, therelationship TY2=(T_(M) -TSX):(TSY-TSX) is valid. The block diagram ofFIG. 5 illustrates the given temperature ranges of switches 31 to 35 infour support locations selected in accordance with FIG. 3, also theinput values of the multiplicators 36 to 41 are mentioned for thespecific temperature range, which have the stated general value.

When the motor temperature is between two support locations, the twooutput values of the supporting locations are measured by the supportinglocations depending on the distance of the motor temperature from thesupporting faces. If the motor temperature is directly on one of thesupporting locations, the output value on this supporting location isonly measured with the factor one.

The described correction of the precontrol of the idling speedregulation of an internal combustion engine encompasses, in accordancewith FIGS. 1 and FIG. 3, only the dependency of the correction from theprecontrol from one variable. However, its is also possible to make theprecontrol dependent from two variables. This does not result in twodimensional characteristics curves as illustrated in FIG. 3, forexample, but three dimensional characteristics curves. Above all, withthe assistance of the direct correction of the precontrol, asillustrated in the two block diagrams of FIGS. 4 and FIG. 5, it ispossible in a particularly advantageous manner to correct these threedimensional performance graphs with the assistance of supportinglocations and corresponding interpolations in a simple manner. Thecalculation of the correcting values for the individual supportlocations requires only a little more effort in comparison with the twodimensional characteristics curve. The equations for these correctingvalues result in analog form with respect to the stated generalequations of the correcting values, as stated in conjunction with theblock diagram of FIG. 5.

FIG. 6 illustrates a further realisation of a correction of theprecontrol of the idling speed regulation of an internal combustionengine. The reference numeral 51 designates an idling speed regulatorwith an I-component. Reference numeral 52 designates a limiting member,reference numeral 53 denotes a counter and reference numeral 54indicates a dead time member. A reverse switch is denoted by referencenumeral 55, while a switch is designated with reference numeral 56. Theidling speed regulator 51 is admitted at its input with the speeddifferential signal ND and generates in dependency therefrom theregulating output signal RA. The limiting member 52, the counter 53, thedead time member 54 and one of the two connecting points of the reverseswitch 55 form a series circuit, whereby the regulating output signal RAis fed at the input of the limiting member 52. The second connectingpoint of the reverse switch 55 is also admitted with the regulatingoutput signal RA. Finally, the common connecting point of the reverseswitch 55 is connected with the switch 56, whose free end influences theprecontrol of the idling speed regulation of the internal combustionengine, either indirectly or directly.

The limiting member 52 has the task to limit the regulating outputsignal RA to defined, predeterminable small values. These limitedregulating output signals are then summed up by the counter 53. So thatnot a every small change of the counting value of the counter 53 causesimmediately a direct or indirect correction of the precontrol. The deadtime member 54 has the task to generate an output signal only when thecounting value of the counter 53 exceeds a defined, predeterminablevalue. In the normal driving operation the reverse switch 55 is soswitched that it connects the dead time member 54 with switch 56. Thereverse switch can only be brought into a different position fordiagnostic purposes, for example, by means of an external manipulation,so that the limiting member 52, the counter 53, and the dead time member54 are short circuited. The switch 56 is only closed when the internalcombustion engine is not in its idling speed. Consequently, nocorrection of the precontrol occurs during the operating condition ofthe idling speed, but only outside of the idling speed operation. Again,it should be noted that the output signal of the switch 56 canindirectly correct the precontrol of the idling speed regulation analogwith respect to FIGS. 1 and 2, on the one hand, and can also performthis correction directly, on the other hand, as illustrated in the FIGS.3 to 5.

I claim:
 1. Method for controlling and regulating the idling speed ofthe internal combustion engine, comprising the steps of generatingoperating characteristics signals which characterize an operationalcondition of the internal combustion engine with sensors, providing anidling speed regulator (10) having an integral component, providing aprecontrol (20) of the idling speed of the internal combustion enginedepending from the temperature as one of the operational values of theinternal combustion engine for generating precontrol signals (KV),providing precontrol correcting means and regulating the idling speed bysaid regulator in dependency from the precontrol of the idling speed,wherein the precontrol is corrected in dependency from the operationalcondition of the internal combustion engine by addingtemperature-dependent correcting signals from a connecting point (14)between said precontrol and said correcting means to said precontrolsignals.
 2. Method in accordance with claim 1, characterized in that theprecontrol is directly controlled by changing the values of theprecontrol.
 3. Method in accordance with claim 1, wherein the precontrolis only corrected in the decoupled operational condition of the internalcombustion engine.
 4. Method in accordance with claim 3, wherein theinternal combustion engine is exactly in its decoupled operationalcondition when the amount of the speed difference between a desiredregulation speed and the actual speed is below a defined,predeterminable speed differential threshold and when the output signalof the idling speed regulator is also below a defined, predeterminablethreshold.
 5. Method in accordance with claim 3, wherein the internalcombustion engine is exactly in its decoupled operational stage when adrive speed drop of the internal combustion engine falls below adefined, predeterminable value.
 6. Method in accordance with claim 5,wherein in an internal combustion engine with an automatic-drive-switchthe precontrol is corrected only when the automatic-drive-switch is notin a drive position.
 7. Method in accordance with claim 1, wherein theprecontrol is corrected only when the drive speed of a motor vehiclebeing driven by the internal combustion engine falls below a defined,predetermined drive speed.
 8. Method in accordance with claim 1, whereinthe precontrol is only corrected when the internal combustion engine isin maintenance.
 9. Method in accordance with claim 1, wherein theprecontrol is divided into a plurality of ranges by means of equations.10. Method in accordance with claim 9, wherein the total precontrol iscorrected.
 11. Method in accordance with claim 1, wherein the precontrolis stated by means of individual support locations and intermediatelydisposed corresponding interpolations.
 12. Method in accordance withclaim 11, wherein only the support locations are corrected.
 13. Methodin accordance with claim 1, wherein the precontrol depends not only fromone, but from a plurality of variables.
 14. Device for controlling andregulating the idling speed of an internal combustion engine, comprisingsensors for generating operating characteristics signals whichcharacterize an operational condition of the internal combustion engine,computer means providing idling speed control and a precontrol of theidling speed control of the internal combustion engine depending fromthe temperature as one of the operational values of the internalcombustion engine, means for regulating the idling speed in dependencyfrom the precontrol of the idling speed, and means for correcting theprecontrol in dependence from the operational condition of the internalcombustion engine by adding temperature-dependent correcting signals toprecontrol signals.
 15. Device in accordance with claim 14, wherein theprecontrol correcting means include at least one intergrator.
 16. Devicein accordance with claim 14, wherein at least one multiplicator is usedin said means for correcting precontrol.
 17. Device in accordance withclaim 14, wherein the total precontrol is influenced with the assistanceof the means for correcting the precontrol.
 18. Device in accordancewith claim 14, wherein the means for correcting the precontrol influenceonly support values of the precontrol.
 19. Device in accordance withclaim 18, wherein only neighboring support values are influenced.